HD74AC538
1-of-8 Decoder with 3-State Output
ADE-205-397 (Z)
1st. Edition
Sep. 2000
Description
The HD74AC538 decoder/demultiplexer accepts three Address (A0 to A2) input signal and decodes them
to select one of eight mutually exclusive outputs. A polarity control input (P) determines whether the
outputs are active LOW or active HIGH. A HIGH signal on either of the active LOW output Enable (OE)
inputs forces all outputs to the high impedance state. Two active HIGH and two active LOW input enables
are available for easy expansion to 1-of-32 decoding with four packages, or for data demultiplexing to 1-of-
8 or 1-of-16 destinations.
Features
• Output Polarity Control
• Data Demultiplexing Capability
• Multiple Enables for Expansion
• Outputs Source/Sink 24 mA
HD74AC538
2
Pin Arrangement
1
2
3
4
5
6
7
8
9
10 11
12
13
14
15
16
17
18
19
20 VCC
O3
O4
A2
E1
E2
O2
O1
O0
OE1
OE2
A0
A1
O5
O6
GND
E3
E4
P
O7
(Top view)
Logic Symbol
PA0
E1
O0O1O2O3O4O5O6O7
E2
E3
E4
OE1
OE2
A1A2
HD74AC538
3
Pin Names
A0 to A2Address Inputs
E1, E2Enable Inputs (Active LOW)
E3, E4Enable Inputs (Active HIGH)
P Polarity Control Input
OE1, OE2Output Enable Inputs (Active LOW)
O0 to O73-State Outputs
Logic Diagram
O7O6O5O4O3O2O1O0
A2
A1
A0
P
E1
E2
E3
E4
OE1
OE2
HD74AC538
4
Truth Table
Inputs Outputs
Function OE1OE2E1E2E3E4A2A1A0O0O1O2O3O4O5O6O7
High impedance H X XXXXXXXXZZZZZZZ
ZHXXXXXXXZZZZZZZZ
Disable L L H X X X X X X Outputs equal input
LLXHXXXXX
LLXXLXXXX
LLXXXLXXX
Active HIGH output L L L L H H L L L H L L LLLLL
(P = L) LLLLHHLLHLHLLLLLL
LLLLHHLHLLLHLLLLL
LLLLHHLHHLLLHLLLL
LLLLHHHLLLLLLHLLL
LLLLHHHLHLLLLLHLL
LLLLHHHHLLLLLLLHL
LLLLHHHHHLLLLLLLH
Active LOW output L L L L H H L L L L H H HHHHH
(P = L) LLLLHHLLHHLHHHHHH
LLLLHHLHLHHLHHHHH
LLLLHHLHHHHHLHHHH
LLLLHHHLLHHHHLHHH
LLLLHHHLHHHHHHLHH
LLLLHHHHLHHHHHHLH
LLLLHHHHHHHHHHHHL
H : High Voltage Level
L : Low Voltage Level
X : Immaterial
Z : High Impedance
DC Characteristics (unless otherwise specified)
Item Symbol Max Unit Condition
Maximum quiescent supply current ICC 80 µAV
IN = VCC or ground, VCC = 5.5 V,
Ta = Worst case
Maximum quiescent supply current ICC 8.0 µAV
IN = VCC or ground, VCC = 5.5 V,
Ta = 25°C
HD74AC538
5
AC Characteristics: HD74AC538
Ta = +25°C
CL = 50 pF Ta = –40°C to +85°C
CL = 50 pF
Item Symbol VCC (V)*1Min Typ Max Min Max Unit
Propagation delay tPLH 3.3 1.0 10.5 17.5 1.0 20.0 ns
An to On5.0 1.0 8.0 12.5 1.0 14.0
Propagation delay tPHL 3.3 1.0 9.5 17.5 1.0 20.0 ns
An to On5.0 1.0 7.0 12.0 1.0 14.0
Propagation delay tPLH 3.3 1.0 11.0 19.5 1.0 23.0 ns
E1, or E2 to On5.0 1.0 8.0 14.5 1.0 16.5
Propagation delay tPHL 3.3 1.0 10.0 19.5 1.0 23.0 ns
E1, or E2 to On5.0 1.0 8.0 14.5 1.0 16.5
Propagation delay tPLH 3.3 1.0 11.0 19.5 1.0 23.0 ns
E3, or E4 to On5.0 1.0 8.5 14.5 1.0 17.0
Propagation delay tPHL 3.3 1.0 10.5 20.0 1.0 23.5 ns
E3, or E4 to On5.0 1.0 8.0 15.0 1.0 18.0
Propagation delay tPLH 3.3 1.0 10.5 15.5 1.0 17.5 ns
P to On5.0 1.0 9.0 11.0 1.0 12.5
Propagation delay tPHL 3.3 1.0 9.0 15.0 1.0 17.0 ns
P to On5.0 1.0 7.5 10.5 1.0 11.5
Propagation delay tPZH 3.3 1.0 7.0 14.0 1.0 15.5 ns
OEn to On5.0 1.0 5.0 8.5 1.0 9.5
Propagation delay tPZL 3.3 1.0 8.5 16.5 1.0 19.0 ns
OEn to On5.0 1.0 5.5 9.5 1.0 11.5
Propagation delay tPHZ 3.3 1.0 7.0 14.0 1.0 15.5 ns
OEn to On5.0 1.0 6.0 10.5 1.0 11.5
Propagation delay tPLZ 3.3 1.0 9.0 14.5 1.0 17.0 ns
OEn to On5.0 1.0 7.0 10.5 1.0 12.0
Note: 1. Voltage Range 3.3 is 3.3 V ± 0.3 V
Voltage Range 5.0 is 5.0 V ± 0.5 V
Capacitance
Item Symbol Typ Unit Condition
Input capacitance CIN 4.5 pF VCC = 5.5 V
Power dissipation capacitance CPD 100 pF VCC = 5.0 V
HD74AC538
6
Package Dimensions
Hitachi Code
JEDEC
EIAJ
Mass
(reference value)
DP-20N
—
Conforms
1.26 g
Unit: mm
0.51 Min
2.54 Min 5.08 Max
7.62
0.25
+ 0.11
– 0.05
2.54 ± 0.25 0.48 ± 0.10
24.50
25.40 Max
0.89 1.30
6.30
7.00 Max
110
1120
0° – 15°
1.27 Max
Hitachi Code
JEDEC
EIAJ
Mass
(reference value)
FP-20DA
—
Conforms
0.31 g
Unit: mm
*Dimension including the plating thickness
Base material dimension
*0.42 ± 0.08
0.12
0.15
M
20
10
1
*0.22 ± 0.05
0.80 Max
11
12.6
5.5
2.20 Max
13 Max
0° – 8°
0.70 ± 0.20
+ 0.20
– 0.30
7.80
1.27
0.10 ± 0.10
1.15
0.40 ± 0.06
0.20 ± 0.04
HD74AC538
7
Hitachi Code
JEDEC
EIAJ
Mass
(reference value)
FP-20DB
Conforms
—
0.52 g
Unit: mm
*Dimension including the plating thickness
Base material dimension
0.12
0.15
0° – 8°
M
20 11
0.20 ± 0.10
1
1.27
10
12.8
13.2 Max
7.50
2.65 Max
*0.27 ± 0.05
*0.42 ± 0.08
+ 0.57
– 0.30
0.70
+ 0.25
– 0.40
10.40
1.45
0.935 Max
0.40 ± 0.06
0.25 ± 0.04
Hitachi Code
JEDEC
EIAJ
Mass
(reference value)
TTP-20DA
—
—
0.07 g
Unit: mm
*Dimension including the plating thickness
Base material dimension
0.50 ± 0.10
0° – 8°
*0.17 ± 0.05
6.40 ± 0.20
0.10
1.10 Max
0.13 M
0.65
110
20 11
4.40
6.50
6.80 Max
*0.22
+0.08
–0.07
0.07
+0.03
–0.04
1.0
0.65 Max
0.20 ± 0.06
0.15 ± 0.04
HD74AC538
8
Cautions
1. Hitachi neither warrants nor grants licenses of any rights of Hitachi’s or any third party’s patent,
copyright, trademark, or other intellectual property rights for information contained in this document.
Hitachi bears no responsibility for problems that may arise with third party’s rights, including
intellectual property rights, in connection with use of the information contained in this document.
2. Products and product specifications may be subject to change without notice. Confirm that you have
received the latest product standards or specifications before final design, purchase or use.
3. Hitachi makes every attempt to ensure that its products are of high quality and reliability. However,
contact Hitachi’s sales office before using the product in an application that demands especially high
quality and reliability or where its failure or malfunction may directly threaten human life or cause risk
of bodily injury, such as aerospace, aeronautics, nuclear power, combustion control, transportation,
traffic, safety equipment or medical equipment for life support.
4. Design your application so that the product is used within the ranges guaranteed by Hitachi particularly
for maximum rating, operating supply voltage range, heat radiation characteristics, installation
conditions and other characteristics. Hitachi bears no responsibility for failure or damage when used
beyond the guaranteed ranges. Even within the guaranteed ranges, consider normally foreseeable
failure rates or failure modes in semiconductor devices and employ systemic measures such as fail-
safes, so that the equipment incorporating Hitachi product does not cause bodily injury, fire or other
consequential damage due to operation of the Hitachi product.
5. This product is not designed to be radiation resistant.
6. No one is permitted to reproduce or duplicate, in any form, the whole or part of this document without
written approval from Hitachi.
7. Contact Hitachi’s sales office for any questions regarding this document or Hitachi semiconductor
products.
Hitachi, Ltd.
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Tel: Tokyo (03) 3270-2111 Fax: (03) 3270-5109
Copyright Hitachi, Ltd., 2000. All rights reserved. Printed in Japan.
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